Abstract: A vehicle includes a vehicle body, a door, a step, a driving device for moving the step between an extending position and a retracting position, an on-board diagnostics for obtaining a state information of the door and having an interface, a vehicle data flow reading module, an emitter, a receiver and a controller. The on-board diagnostics is mounted on the vehicle body. The vehicle data flow reading module is coupled with the interface. The emitter is coupled with the vehicle data flow reading module and configured to emit the state information. The receiver is configured to receive and decode the state information from the emitter. The controller is coupled with the driving device and the receiver and configured to control the driving device to move the step between the extending position and the retracting position based on the state information.